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NetBSD Security Advisory 2007-002
=================================
Topic: Integer overflows in Render and DBE extensions
Version: NetBSD-current: source prior to January 10, 2007
NetBSD 4.0_BETA2: affected
NetBSD 3.1: affected
NetBSD 3.0.*: affected
NetBSD 3.0: affected
NetBSD 2.1: affected
NetBSD 2.0.*: affected
NetBSD 2.0: affected
pkgsrc: xorg-server-6.9.0nb13 and earlier
Severity: Potential local privilege escalation
Fixed: NetBSD-current: January 10, 2007
NetBSD-4 branch: January 11, 2007
NetBSD-3-1 branch: January 11, 2007
NetBSD-3-0 branch: January 11, 2007
NetBSD-3 branch: January 11, 2007
NetBSD-2-1 branch: January 29, 2007
NetBSD-2-0 branch: January 29, 2007
NetBSD-2 branch: January 29, 2007
pkgsrc: xorg-server-6.9.0nb14 corrects the issue
Abstract
========
There are integer overflows present in the Render and DBE extensions as
supplied with both XFree86 and X11R7.0. This can potentially lead
to arbitrary code execution. These vulnerabilities can be triggered
by a user sending specifically crafted X protocol requests.
These vulnerabilities have been assigned CVE references CVE-2006-6101,
CVE-2006-6102 and CVE-2006-6103.
Technical Details
=================
There are three separate integer overflows that are present:
* ProcRenderAddGlyphs() function in the Render extension
* ProcDbeGetVisualInfo() function in the DBE extension
* ProcDbeSwapBuffers() function in the DBE extension
Vulnerabilities present can potentially lead to arbitrary code execution.
Solutions and Workarounds
=========================
While X11R7.0 from X.Org is in both the HEAD and netbsd-4 branches it
is currently not integrated fully into the base distribution. No NetBSD
releases contain X11R7.0 binaries and as such it is not necessary to
rebuild anything from source. The instructions below will patch the
relevant X11R7.0 source files so that if users are experimenting with
X11R7.0 it will contain the necessary security fixes.
A possible temporary workaround for this issue is to disable the DBE
and render extensions in your X Server configuration. To do this under
the Modules section of the X Server configuration file comment out the
lines containing:
Load "DBE"
Load "render"
For X.Org the configuration file will be xorg.conf and for XFree86
it will be XF86config. This may impact the appearance of applications
run in X Windows.
XFree86-based X servers are included in the NetBSD base distribution,
and will need to be rebuilt. The following instructions describe how
to upgrade your XFree86 binaries by updating your source tree and
rebuilding and installing a new version of XFree86.
* NetBSD-current:
Systems running NetBSD-current dated from before 2007-01-10
should be upgraded to NetBSD-current dated 2007-01-11 or later.
The following files need to be updated from CVS HEAD:
xfree/xc/programs/Xserver/dbe/dbe.c
xfree/xc/programs/Xserver/render/render.c
xorg/xserver/xorg/dbe/dbe.c
xorg/xserver/xorg/render/render.c
To update from CVS, re-build, and re-install XFree86:
# cd xsrc
# cvs update xfree/xc/programs/Xserver/dbe/dbe.c
# cvs update xfree/xc/programs/Xserver/render/render.c
# cvs update xorg/xserver/xorg/dbe/dbe.c
# cvs update xorg/xserver/xorg/render/render.c
# make build
* NetBSD 3.*:
Systems running NetBSD 3.* sources dated from before
2007-01-11 should be upgraded from NetBSD 3.* sources dated
2007-01-12 or later.
The following files need to be updated from the
netbsd-3, netbsd-3-0 or netbsd-3-1 CVS branch:
xfree/xc/programs/Xserver/dbe/dbe.c
xfree/xc/programs/Xserver/render/render.c
To update from CVS, re-build, and re-install XFree86:
# cd xsrc
# cvs update -r <branch_name> \
xfree/xc/programs/Xserver/dbe/dbe.c
# cvs update -r <branch_name> \
xfree/xc/programs/Xserver/render/render.c
# make build
* NetBSD 2.*:
Systems running NetBSD 2.* sources dated from before
2007-01-29 should be upgraded from NetBSD 2.* sources dated
2007-01-30 or later.
The following files need to be updated from the
netbsd-2, netbsd-2-0 or netbsd-2-1 CVS branch:
xfree/xc/programs/Xserver/dbe/dbe.c
xfree/xc/programs/Xserver/render/render.c
To update from CVS, re-build, and re-install XFree86:
# cd xsrc
# cvs update -r <branch_name> \
xfree/xc/programs/Xserver/dbe/dbe.c
# cvs update -r <branch_name> \
xfree/xc/programs/Xserver/render/render.c
# make build
Thanks To
=========
Sean Larsson of iDefense Labs is credited with the discovery of these issues.
Revision History
================
2007-03-08 Initial release
More Information
================
Advisories may be updated as new information becomes available.
The most recent version of this advisory (PGP signed) can be found at
ftp://ftp.NetBSD.org/pub/NetBSD/security/advisories/NetBSD-SA2007-002.txt.asc
Information about NetBSD and NetBSD security can be found at
http://www.NetBSD.org/ and http://www.NetBSD.org/Security/.
Copyright 2007, The NetBSD Foundation, Inc. All Rights Reserved.
Redistribution permitted only in full, unmodified form.
$NetBSD: NetBSD-SA2007-002.txt,v 1.1 2007/03/05 23:33:14 adrianp Exp $
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